Swan neck deformity is seen in: March 2013 (a, c, e)
**Core Concept**
Swan neck deformity is a type of finger deformity characterized by hyperextension of the proximal interphalangeal (PIP) joint and flexion of the distal interphalangeal (DIP) joint. This deformity is often associated with **rheumatoid arthritis** and other conditions affecting the balance of flexor and extensor tendons in the hand.
**Why the Correct Answer is Right**
The correct answer is related to conditions that affect the balance of tendons in the hand, leading to swan neck deformity. In **rheumatoid arthritis**, inflammation and tendon imbalance can cause this deformity.
**Why Each Wrong Option is Incorrect**
**Option A:** Not directly related to swan neck deformity.
**Option B:** Not directly related to swan neck deformity.
**Option D:** Not directly related to swan neck deformity.
**Clinical Pearl / High-Yield Fact**
Swan neck deformity is a classic finding in **rheumatoid arthritis**, and its presence can indicate chronic disease.
**Correct Answer:** C. Rheumatoid arthritis